For more than a century, scientists have been attempting to harness the immune system to fight cancer — trying to get the antibodies and cells that protect us from bacteria and viruses to kill diseased cells. Every once in a while, a tantalizing success occurred. But time and again the treatment could not be repeated.
The case begins with a drug called ipilimumab, approved in 2011 for advanced melanoma treatment. The drug turns the immune system into a cancer-killer, bringing some patients back from the brinkof death. Melanoma is one of the deadliest forms of skin cancer, striking 76,000 Americans and killing more than 9,000 every year. Because there are few treatments for advanced melanoma, the new drug was greeted with excitement by doctors and patients. But ipilimumab, sold under the brand named Yervoy by Bristol Myers Squibb, works in only 10 percent to 20 percent of patients.
Until now, no one knew why.